I remember being told when i was in highschool, it was always pronounced "pell mell" Is this still true?

Never been true in my lifetime, Bill - unless you wanted to say it like a real (and probably pretentious) toff.

"pell mell" [sic] is used, though, meaning running around like crazy. Ah, here it is in M-W:

Main Entry: pell-mell
Pronunciation: "pel-'mel
Function: adverb
Etymology: Middle French pelemele
Date: 1596
1 : in mingled confusion or disorder
2 : in confused haste
- pell-mell adjective or noun